When you're installing a new kitchen countertops, installing the sink means you're near the end. Most sinks come with a paper or cardboard template to help outline the area you're going to cut out. Quite often, the cardboard template is part of the shipping box for the sink. Use a utility knife to cut the template from the box. Just be careful not to cut yourself, and be sure to follow the line so that the template is as straight as possible.
In some cases, the backsplash interferes with making the rear cut for a sink cutout. In that case, you must make the cut with the countertop upside down, so make the sink cutout after testing the fit but before joining any miter joints or attaching the countertop.
You can order your countertops pre-cut, including a hole for the sink, but do so only if you know that all your measurements are absolutely, positively dead-on, with no chance of being off by even a little bit.
If your sink doesn't come with a template, or if you bought a good-looking closeout-sale sink without a box, you can make your own by laying the sink on the countertop, making sure the sink is positioned evenly, and tracing around the edges with a pencil.
To cut a hole for a sink, it's easiest to use a jigsaw, which allows for great control.
Always, always, always use a new jigsaw blade. An old or dull blade can chip the laminate along the cutting line.
Drill two starter holes in opposite corners just inside the cutting line. Use a 3/4-inch spade bit and drill through the laminate and substrate.
Don't worry if the cut edge is rough. The rim of the sink will cover it. You're cutting into sections that you'll eventually cut out and toss (in the garbage, not just up in the air).
Place the blade of the jigsaw in the starter hole and line up the blade exactly on the cutting line.
If the backsplash interferes with the saw shoe and prevents making the cut, turn the countertop over to complete the cut from the underside. If you choose this method, make this cut first.
Cut slowly along the line.
Don't be in a rush — let the saw do the work. Again, don't worry about any little chips that may occur. The sink lip will cover them.
To make a clean, safe cut, ask a helper to support the cutout area so that the piece doesn't drop and cause the saw blade to bind. Make sure your helper wears heavy gloves and eye protection.